[en] The electronic bandstructure of zirconium, which has a HCP lattice structure, has been calculated using crystal potentials which include the effect of correlation as well as exchange. Two methods, one due to Kohn and Sham and the other to Overhauser are used for calculating the exchange and correlation contributions to the crystal potential. The calculations show some changes from the results of the previous workers. With the inclusion of correlation the levels around the symmetry point K become well separated, and the entire set of bands is shifted by about 0.25 Ryd. The density of states has been obtained using one of the potentials. The bandstructure results are used to calculate the momentum density distribution of positron annihilation along the c axis. (author)